System for identifying premature rupture of membrane during pregnancy

ABSTRACT

An article for the identification of the premature rupture of a membrane during pregnancy is disclosed. The article comprises a pad having an upper outer layer, a lower outer layer, and an intermediate pH-responsive component. A double-sided adhesive strip is attached to the lower outer layer. The upper outer layer is composed of a liquid permeable material. Intermediate of the upper out layer and the inner outer layer is a pH-sensitive component. This intermediate layer is a pH-sensitive material and may be one of a variety of such materials, although a preferred material is nitrazine paper. In the presence of an alkaline fluid, such as amniotic fluid, the pH-sensitive material responds by turning to a purple-blue color. The change in color acts as a visual indicator to the wearer of the possible presence of amniotic fluid outside of the amniotic sac.

TECHNICAL FIELD

The present invention is generally directed to an article for theidentification of the premature rupture of a membrane during pregnancy.More particularly, the present invention is directed to an indicatingarticle in the form of a multilayered pad that is fitted to theundergarment of a user. The multilayered pad includes a treatedcomponent which responds to the presence of amniotic fluid as adischarge.

BACKGROUND ART

The amnion develops around the embryo during the second week followingfertilization. This is the second membrane to appear after the placentaforms around the chorion. The margin of the amnion is attached to theperiphery of the embryonic disk. Eventually, as the embryo grows, theamnion fuses with the chorion surrounding it, and the two membranesbecome a single amniochorionic membrane. Amniotic fluid fills theamniochorionic membrane to provide a watery environment to define aprotective space for the growing embryo.

Ordinarily the amniochorionic membrane acts as a primary barrier tobacteria and other potentially damaging organisms by providing aprotected, substantially sealed environment throughout the developmentof the embryo until it ruptures subsequent to the onset of labor.However, this environment is occasionally compromised when it isprematurely ruptured prior to the onset of labor. Technically, prematurerupture of the membrane can occur at any time during the forty weeks ofgestation. Although definitions vary, "premature rupture of themembrane" refers to rupture of the amniochorionic membrane prior to theonset of labor at any time. In either case, a ruptured membrane poses aconsiderable risk of infection to both mother and fetus.

Occasionally, rupturing of the membrane follows invasive techniques suchas amniocentesis and may lead to infection of the developing fetus. Thisrupture occurs in about 1 out of every 200 procedures. For womenundergoing an amniocentesis in the second trimester, detection of arupture of the membrane is critical. A gross rupture of fluid could bepotentially catastrophic for the developing fetus, as adequate amnioticfluid is a necessity to assure proper lung development, especially priorto 23 weeks.

Beyond the obvious compromise of the membrane caused by amniocentesis,the exact cause of premature rupture is not known. Possible causesinclude infection, cervical incompetence, and decreased strength of themembrane. Regardless of the cause, with the premature rupture of themembrane, the fetus must be promptly delivered when the mother becomesclinically infected or the fetus shows signs of potential compromise. Ineither situation, if left untreated, possible death to the fetus and themother could result. It is noteworthy that chorioamnionitis is presentin about 5 to 10 percent of all deliveries and, significantly, is thereason for about 10 percent of all perinatal deaths.

In the event of premature rupture of the membrane, the timing for thedelivery of the baby becomes critical, as the risk of intrauterineinfection increases significantly as more time passes following rupture.Accordingly, it becomes critical to provide a method of early detectionof rupture. The problem is that leaking amniotic fluid--the telltalesign of rupture--is frequently confused by the mother with her own urineor vaginal discharge. (The leakage of urine during pregnancy[particularly during the latter stages] is frequent due to increasedpressure on the bladder, thus adding to the overall incidence of falsepositives.) This results in many false alarms and unnecessary trips toeither the doctor's office or to the hospital for evaluation of thepregnant woman to rule out possible rupture of the membrane. These tripslead to wasted time and energy on the part of both the patient and thephysician as well as considerable expense to the health care system. Ahospital audit revealed an average cost of $250.00 per visit to rule outrupture of the membrane.

Once the pregnant woman identifies leakage, today she has no practicalchoice but to visit her physician. Because the presence of leaking urineis fleeting, the attending physician must undertake one or more tests inthe office to determine whether or not there has been a rupture of themembrane. The conventional test is for the physician to observe thecervix after employing a speculum in an effort to identify pooling offluid behind the cervix. The physician then applies a swab of pH paperheld by a forceps to the fluid located in the area of the cervix todetermine whether or not amniotic fluid is present by observing a changein color. Amniotic fluid is alkaline and the pH paper reacts to itspresence by turning purple-blue. While functional, the examination isfar more often than not unnecessary. It is also impractical, leading toparticular discomfort for the patient and lost time for the physician.

Other in-office or in-hospital tests for the presence of amniotic fluidare known. For example, in U.S. Pat. No. 4,357,945, issued on Nov. 9,1982 to Janko for DEVICE FOR TESTING AND RUPTURING AMNIOTIC MEMBRANE, afinger-mounted medical testing device is disclosed which tests theintactness of the amniotic membrane. The device of Janko is providedwith a pH-responsive material. Upon insertion into the cervix, theindicator material is exposed to the local environment.

In U.S. Pat. No. 5,425,377, issued on Jun. 20, 1995 to Caillouette forPH MEASUREMENT OF BODY FLUID, a swab is provided which includes a pHindicator for measuring the pH of vaginal moisture.

Other techniques for use in-office or in-hospital are provided in: U.S.Pat. No. 5,281,522 issued on Jan. 25, 1994 to Senyei et al. for REAGENTSAND KITS FOR DETERMINATION OF FETAL FIBRONECTIN IN A VAGINAL SAMPLE;U.S. Pat. No. 5,096,830, issued on Mar. 17, 1992 to Senyei et al. forPRETERM LABOR AND MEMBRANE RUPTURE TEST; and U.S. Pat. No. 5,554,504,issued on Sep. 10, 1996 to Rutanen for DIAGNOSTIC METHOD FOR DETECTINGTHE RUPTURE OF FETAL MEMBRANES.

While these various methods provide approaches to testing for amnioticfluid, they do not overcome the basic problem of requiring aprofessional medical technician to deal in-office or in-hospital withthe administration of relevant tests. Further complicating the scenariois the fact that a ruptured amniotic membrane may lead to only atemporary leakage of amniotic fluid, with another leaking episode tooccur at a later time. In the meantime, the patient may become infected,with the potential result of great injury to both the baby and themother.

It is therefore an object of the present invention to overcome thedisadvantages associated with known techniques for identifying leakingamniotic fluid and possible rupture of the amniochorionic membrane.

It is a further object of the present invention to provide an articlewhich allows the early identification of the discharge of amniotic fluidwithout the necessity of a visit to a doctor's office or a hospital. Yetanother object of the present invention is to provide such an articlewhich may be used with minimal inconvenience to the user.

Still a further object of the present invention is to provide such anarticle which is worn like a sanitary napkin or pad and which may alsoprovide the function of such sanitary items.

Finally, in these times of cost containment, the potential savings froma device which could eliminate unnecessary visits to the physician'soffice or to the hospital could be tremendous. An additional object ofthe present invention is to provide such an article which can minimizefalse positives and have a substantial impact on and impart an economicbenefit to the health care system.

SUMMARY OF THE INVENTION

The present invention achieves these objectives in an indicating devicethat comprises a pad having an upper outer layer, a lower outer layer,and an intermediate pH-responsive layer. A double-sided adhesive stripis attached to the lower outer layer.

The upper outer layer and the lower outer layer are attachedsubstantially the same size and are attached to one another along theirperipheral edges. The upper outer layer and the lower outer layer arepreferably composed of a non-woven material, such as a spunbondedmaterial, or may be composed of a webbed construction which provides thedevice with bulk and loft. Optionally, the lower outer layer, whichcomprises the lower undergarment contacting surface, is comprised of apolymerized barrier film.

The upper outer layer and the lower outer layer define substantially thesame width and length. The overall size of the article may be adjustedas desired. The article may or may not be designed to achieve a highabsorbency function. (While not necessary directed to absorbency as in amenstrual pad, the article of the present invention may be configured soas to provide this added function.)

Intermediate of the upper out layer and the inner outer layer is apH-sensitive layer. This intermediate layer is a pH-sensitive materialand may be one of a variety of such materials, although a preferredmaterial is NITRAZINE® chemical indicator paper (trademark; BraccoDiagnostics, Inc, Eae Princeton N.J. In the presence of an alkalinefluid, such as amniotic fluid, the pH-sensitive material responds byturning to a purple-blue color. The change in color acts as a visualindicator to the wearer. Conversely, a change to the other end of theColor Scale, such as a yellow, indicates acidity, indicating to thewearer that a normal condition is present.

Fitted to the lower outer layer is at least one fastening adhesive stripwhich provides an adhesive attachment means for attaching the article tothe underwear of the user.

As an alternate embodiment of the present invention, a dropper bottlecontaining a pH-sensitive liquid may be provided. The liquid isselectively placed on a feminine pad and the pad is worn in its usualmanner. As with the article defined above, a change in color to thepurple-blue end of the Color Scale indicates that amniotic fluid may bepresent in the wearer's discharge.

Other objects and advantages of the present invention will be madeapparent as the description progresses.

BRIEF DESCRIPTION OF THE DRAWINGS

The various advantages of the present invention will become apparent toone skilled in the art by reading the following specification andappended claims and by referencing the following drawings, in which:

FIG. 1 is a perspective view showing the manner of placing theindicating article of the present invention to an undergarment;

FIG. 2 is a perspective view of the article of the present inventionwith its upper outer layer partially peeled away from the lower outerlayer to reveal the intermediate pH-sensitive layer;

FIG. 3 is a transverse cross-sectional view of the indicating article ofthe present invention taken along lines 3--3 of FIG. 2 illustrating itsmultilayered construction;

FIG. 4 is a top plan view of the indicating article of the presentinvention demonstrating to the wearer the presence of an acidic flow;

FIG. 5 is a view similar to that of FIG. 4 but demonstrating to thewearer the presence of an alkaline fluid; and

FIG. 6 is a perspective view of an alternate embodiment of the presentinvention in the form of a pH-indicating fluid being distributed on afeminine hygiene pad.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the indicating article of the presentinvention for use in an undergarment is shown throughout the figures.With respect first to FIG. 1, the article of the present invention,generally illustrated as 10, is shown in place within an undergarment12. The article 10 includes an elongated body 14. The undergarment is ofthe type commonly worn by many women and well-known as a panty. Itcomprises a front section 16, a back section 18, and a crotch portion 20which joins the front and back sections 16 and 18, respectively. Thearticle 10 is utilized by removing its release paper (shown in FIG. 3and discussed below in relation thereto) and thereafter placing it inthe undergarment 12. The elongated body 14 of the indicating article 10is placed in the crotch portion 20 of the undergarment 12 with a firstend 22 extending toward the front section 16 and a second end 24 towardthe back section 18 of the undergarment 12. The lower outer layer of thearticle 10 is in contact with the inner surface of the center crotchportion 20 of the panty 12. The adhesive strips maintain the elongatedbody 14 in position.

FIG. 2 is a perspective view of the article 10. The article 10 includesan upper outer layer 26 and a lower outer layer 28. The layers 26 and 28may be made of a non-woven material, such as a spunbonded material.Alternatively, the layers 26 and 28 may be composed of a webbedconstruction which provides the device with bulk and loft.

The upper outer layer 26 is preferably liquid permeable to allow bodyfluids to substantially pass. The upper outer layer 26 is also incontact with the wearer's skin. Accordingly, the upper outer layer 26 ispreferably composed of a compliant, soft-feeling material that isnon-irritating to the parts of the user's skin with which it is incontact. The upper outer layer 26 can be made from any of the materialsconventional for this type of use. Non-limiting examples of suitablematerials that can be used as the upper outer layer 26 are non-wovencotton, polyester, polyethylene, polypropylene, nylon and rayon andformed thermoplastic films. The preferred type of material is aspunbonded one that is pervious to liquids but is neverthelessnon-absorbent. The particular material is selected so that the surfaceof the upper outer layer 26 remains dry and is thus more comfortable tothe wearer. The recommended thickness of the upper outer layer 26 isbetween 1 and 2 mils with the preferred thickness being about 1 mil.

The lower outer layer 28, which comprises the lower undergarmentcontacting surface, may be comprised of a polymerized barrier film. Inthis embodiment, the lower outer layer 28 may be composed of apolyethylene film such as that offered by the Clopay Corporation(Cincinnati, Ohio.) under the designation P18-0401 and by EthylCorporation (Terre Haute, Ind.) under the designation XP-39385. Theupper outer layer 26 and the lower outer layer 28 may be composed ofselected materials so as to provide a mere carrier for the pH-sensitivecomponent or may be composed of material such that the article 10 actsadditionally as a sanitary napkin, capable of absorption of body fluids.In this situation, the upper outer layer 26 would still be composed of aliquid permeable material. However, the lower outer layer 28 would beentirely or partially composed of an absorbent material or an additionalabsorbent layer (not shown) would be added between the upper outer layer26 and the lower outer layer 28 with the pH-sensitive component(discussed below with respect to FIG. 2) fitted adjacent the upper outerlayer 26. Where absorbency is desired to allow the article 10 to doubleas an absorbent pad, a suitable absorbent, hydrophilic fiber intended toabsorb and contain liquid may be used. Examples of suitable hydrophilicfiber material include cellulose, modified cellulose, rayon, polyesterssuch as polyethylene terephtalate (DACRON [trademark]), hydrophilicnylon (HYDROFIL [trademark]), and the like. The selection of theparticular material is only controlled by the desired absorbent capacityof the absorbent material.

The upper outer layer 26 and the lower outer layer 28 are joined alongtheir peripheral edges by known methods of joining, including chemicalbonding and physical stitching. As used herein, the term "joined"encompasses configurations whereby an element is directly secured to theother element by affixing the element directly to the other element,configurations whereby the element is indirectly secured to the otherelement by affixing the element to intermediate member(s) which in turnare affixed to the other element, and configurations whereby one elementis integral with another element, i.e., one element is essentially partof the other element.

The article 10 has a pair of opposed sides 30 and 32. The sides 30 and32 are illustrated as being substantially parallel and linear, but it isto be understood that the sides 30 and 32 may be non-linear and maydefine any of a variety of curved lines. For example, the sides 30 and32 may be configured so as to follow the curved, crotch area edges thatdefine the leg holes of an undergarment.

The overall dimensions of the article 10 may be varied as necessarydepending on the size and style of the undergarment and the intended useof the article 10. For example, when the user is lying in the proneposition, there is a tendency for body fluid to gravitate toward eitherthe person's front side or back side, depending on which side the personis lying. The article 10 may accordingly be longer for this purpose, andmay accordingly be particularly desirable for use by those at-risk womenwho are substantially bed ridden during the last weeks of pregnancy.However, with the longitudinal centerline of the article 10 representingthe Y-axis and the transverse centerline representing the X-axis asoriented by reference to a planar Cartesian coordinate system, thepreferred size of the article 10 is between 150 and 170 mm along theY-axis (or the long axis) of the article 10 and between 100 and 125along the X-axis or along the width of the article 10.

The article 10 is provided with a pH-sensitive component 34. Thecomponent 34 defines a strip of a flexible material, such as a strip ofNITRAZINE® chemical indicator paper, which effects a color change inaccordance with acidity or alkalinity. The component 34 is fittedbetween the upper outer layer 26 and the lower outer layer 28.Accordingly, the selection of material for the upper outer layer 26 islimited only by the requirement that the material be selected from thoseof specific density or composure so as to permit the color of thecomponent 34 to be visualized by the wearer by reference to the upperouter layer 26, that is, without having to disassemble the article 10 toverify the color.

While NITRAZINE® chemical indicator paper is the preferred form ofmaterial for indicating pH, other pH indicators could be used as well.Such indicators may be selected from the group consisting ofbromochlorophenol blue sodium salt, bromocresol green ACS, bromocresolgreen sodium salt ACS, bromocresol purple, bromocresol purple sodiumsalt, bromophenol blue ACS, bromophenol blue sodium salt ACS,bromopyrogallol red, bromothymol blue ACS, bromothymol blue sodium saltACS, bromoxylenol blue, calceinifluroexon, calconcarboxylic acid,calmagite, chlorophenol red, o-cresolphthalein, o-cresolphthaleincomplexone, o-cresolphthalein complexone disodium salt, m-cresol purple,m-cresol purple sodium salt, cresol red, cresol red sodium salt,erichrome blue black R, ethyl orange sodium salt, fast sulphone black F,litmus powder, methyl orange ACS, methyl red free acid ACS, methyl redHCL ACS, methyl red sodium salt ACS, methylthymol blue, murexide powder,P.A.N., P.A.R., patent blue VF, phenolphthalein ACS, phenolphthaleinACS, phenol red ACS, phenol red sodium salt ACS, pyrocatechol violet,pyrogallol red, quinaldine red, SPADNS, thorin, thymol blue ACS, thymolblue sodium salt ACS, thymolphtahalein ACS, tropaeolin O, and xylenolorange tetrasodium salt ACS.

FIG. 3 is a transverse cross-sectional view of the article 10 of thepresent invention taken along lines 3--3 of FIG. 2. This viewillustrates the article 10 in place on the crotch portion 10 of theundergarment 12. The article 10 can be configured such that the upperouter layer 26 and the lower outer layer 28 are mere carriers for thepH-sensitive component 34, or may function simultaneously as a femininenapkin or pad or a panty liner or shield. A plurality of fasteningadhesive strips 36 are provided on the underside of the article 10 forremovable attachment to the undergarment 10. Any adhesive or glue usedin the art for such purpose can be used herein, with pressure sensitiveadhesives being preferred. Suitable adhesives are Century A-305-IVmanufactured by the Century Adhesives Corporation and Instant Lok34-2823 manufactured by the National Starch Company. As illustrated, asingle fastening adhesive strip 36 is only of a width that is less thanthat of the elongated body 12 of the article 10. The adhesive strip 36is covered with a release paper (not shown) to keep the strip 36 fromsticking to extraneous surfaces prior to use. Any conveniently availablerelease paper commonly used for such purposes can be used herein.Non-limiting examples of suitable release papers are BL 30 MG-A SiloxEI/O and BL 30 MG-A Silox 4 P/O, both of which are manufactured by theAkrosit Corporation. To employ such a devise, the user would firstremove a release paper and apply the article 10 with a slight pressureto the crotch area 20 of the undergarment 12.

In use, the wearer removes the release tape (not shown) to expose theadhesive strip 36 of the article 10 and places the article 10 in thecrotch portion 20 of her undergarment 12. The user then wears theundergarment 12 in the usual manner, adjusting or removing themoccasionally as required to observe the color status of the article 10.A yellow color of the pH-sensitive component 34 as indicated in FIG. 4demonstrates to the wearer the presence of an acidic flow and can besafely disregarded as urine. Conversely, a visualized purple-blue colorof the pH-sensitive component 34 as illustrated in FIG. 5 woulddemonstrate to the wearer the presence of an alkaline fluid. As notedabove, the alkaline fluid may be a false positive if seminal fluid orblood. However, the only other alkaline fluid possibly present would beamniotic fluid, indicating to the wearer that there is a possiblerupture of the amniotic sac, whereupon a physician should be contacted.In any event, the wearer may dispose of the article 10 after use in amanner consistent with the normal disposal of a feminine pad or napkin.

As an alternate embodiment of the present invention, a liquid form ofthe pH-sensitive component may be used. With reference to FIG. 6, aliquid form of the pH-sensitive component is housed in a bottle 38. Thewearer (not shown) would apply a series of drops of the liquid materialalong the approximate mid-point of the upper, body-facing side of a pador napkin 40. In this embodiment, the wearer would apply and use the pador napkin 40 in a manner similar to that of the embodiment of FIGS. 1through 5 described above.

Those skilled in the art can now appreciate from the foregoingdescription that the broad teachings of the present invention can beimplemented in a variety of forms. Therefore, while this invention hasbeen described in connection with particular examples thereof, the truescope of the invention should not be so limited since othermodifications will become apparent to the skilled practitioner upon astudy of the drawings, specification and following claims.

What is claimed is:
 1. A system for identifying the premature rupture ofa membrane during pregnancy by detecting the presence of amniotic fluidfor use with the pants of a wearer, the system comprising:a pad forplacement in the crotch portion of the pants of the wearer, the padincluding an upper layer and a lower layer; and a pH-sensitive componentfitted to said pad, said pH-sensitive component being changeable betweenone of two colors, said colors including a first color which indicates apH less than that of amniotic fluid and a second color which indicatespH in the range of amniotic fluid.
 2. The system for identifying thepremature rupture of a membrane according to claim 1, wherein saidpH-sensitive component is chemical indicator material.
 3. The system foridentifying the premature rupture of a membrane according to claim 2,wherein said chemical indicator material is a sheet of chemicalindicator paper.
 4. The system for identifying the premature rupture ofa membrane according to claim 1, wherein said pH-sensitive component isin liquid form.
 5. The system for identifying the premature rupture of amembrane according to claim 1, further including at least one adhesivestrip provided on said lower layer of said pad.
 6. The system foridentifying the premature rupture of a membrane according to claim 1,wherein said upper layer is liquid-permeable.
 7. The system foridentifying the premature rupture of a membrane according to claim 1,wherein said lower layer is at least partially liquid-impermeable. 8.The system for identifying the premature rupture of a membrane accordingto claim 1, wherein said lower layer is liquid absorbent.
 9. A pad foridentifying the premature rupture of a membrane during pregnancy bydetecting the presence of amniotic fluid for use with the pants of awearer, the pad comprising:an upper layer; an intermediate component; alower layer, whereby said intermediate component is fitted between saidupper and lower layers, said intermediate component being pH-sensitive,said pH-sensitive intermediate component being changeable between one oftwo colors, said one of two colors including a first color whichindicates a pH outside the range of amniotic fluid and a second colorwhich indicates a pH in the range of amniotic fluid.
 10. The pad foridentifying the premature rupture of a membrane according to claim 9,wherein said intermediate component is chemical indicator material. 11.The pad for identifying the premature rupture of a membrane according to10, wherein said chemical indicator material is a sheet of chemicalindicator paper.
 12. The pad for identifying the premature rupture of amembrane according to claim 9, wherein said pH-sensitive component is inliquid form.
 13. The pad for identifying the premature rupture of amembrane according to claim 9, further including at least one adhesivestrip provided on said lower layer.
 14. The pad for identifying thepremature rupture of a membrane according to claim 9, wherein said upperlayer is liquid-permeable.
 15. The pad for identifying the prematurerupture of a membrane according to claim 9, wherein said lower layer isat least partially liquid-impermeable.
 16. The pad for identifying thepremature rupture of a membrane according to claim 9, wherein said lowerlayer is liquid absorbent.
 17. A method for identifying the prematurerupture of a membrane during pregnancy through the detection of amnioticfluid, the method comprising the steps of:forming a pad for use in thepants of a wearer; fitting said pad with a pH-sensitive component;wearing said pad with said pH-sensitive component for a select period oftime; and visualizing said pH-sensitive component for a sign of changein color, said step of visualizing and differentiating between one oftwo colors, one of said two colors indicating the presence of amnioticfluid, the other of two colors indicating the absence of amniotic fluid.18. The method for identifying the premature rupture of a membraneaccording to claim 17, including the step of fitting said pad with asheet of pH-sensitive material.
 19. The method for identifying thepremature rupture of a membrane according to claim 17, including thestep of fitting said pad with a sheet of chemical indicator paper. 20.The method for identifying the premature rupture of a membrane accordingto claim 17, including applying a pH-sensitive liquid to said pad tocomprise said pH-sensitive component.